I tend to share the same views expressed here: https://www.cultofpedagogy.com/social-justice-resources/
Diversity in an English classroom is vital for student comprehension, acceptance, and just for keeping their attention. I know it is a sensitive issue, but since when has English avoided sensitive topics anyway?
First, learn what your students already know about this issue and what they have already been taught. Besides the points expressed in the link you need to know what ground has already been covered so you can teach them new things. Martin Luther King Jr. probably has already been taught before, so why not talk about mental disabilities or something else to give them a wider range? Covering the same topics over and over again can reduce interest in the topic, seem preachy, and even become condescending!
Not only is this useful for teaching kids new things, but just reading something that is not either written by or starring a standard white character can do wonders! Why not read a piece from India or Mexico? Have a story featuring a person of color or even somebody in a wheelchair? Just reading a story featuring somebody like them can do wonders for someone of these minorities as well as gives those outside of these social groups a view into their lives! I am not talking about making them read The Brief Wonderous Life of Oscar Wao or Precious, but maybe just some short stories or even some comics could help broaden your students’ horizons far more than a generic fantasy story could.